Problem: Simplify to lowest terms. $\dfrac{28}{49}$
Solution: What is the greatest common factor (GCD) of 28 and 49? $28 = 2\cdot2\cdot7$ $49 = 7\cdot7$ $\mbox{GCD}(28, 49) = 7$ $\dfrac{28}{49} = \dfrac{4 \cdot 7}{ 7\cdot 7}$ $\hphantom{\dfrac{28}{49}} = \dfrac{4}{7} \cdot \dfrac{7}{7}$ $\hphantom{\dfrac{28}{49}} = \dfrac{4}{7} \cdot 1$ $\hphantom{\dfrac{28}{49}} = \dfrac{4}{7}$